Research shows several more Ripon sinkholes could appear in future, group warns

Fears have been raised that several more sinkholes could appear in Ripon in the future following research carried out by a community group.

Monday, 14th November 2016, 4:09 pm
Updated Wednesday, 16th November 2016, 4:23 pm
Sinkhole in Ripon - British Geological Survey NERC

The City of Ripon Trust has warned that invasive boreholes, previously created to detect gypsum dissolution, will trigger new water flows causing further sinkholes.

A borehole is any hole drilled or dug into the ground to either extract or investigate the material at that particular time

Stanley Mackintosh, principal of the Trust, warned that there have been a number of these boreholes created in the past, including the former Auction Mart and Jewson site on Bondgate Green.

He said: "My belief is that such boreholes can compromise and destabilize not only the site in question, but also land and property far beyond.

"Sadly, there may now be several or many more such sinkholes –some of them catastrophic– yet to occur in and around Ripon, consequential to invasive borehole activities.

"This includes hundreds of boreholes commissioned by the British Geological Survey in the late 20th century for research purposes."

Twelve families remain homeless after a 66ft sinkhole opened in two back gardens on Magdalen's Close on Wednesday night.

Sinkholes are relatively common in Ripon and are usually caused by the dissolution of thick gypsum deposits beneath the area.

After a 100-year-old building collapsed on Magdalen's Close in 2014, the British Geological Survey said gypsum under the city had dissolved to form a maze-like cave system.

It said in a report that sinkholes appeared in Ripon every two or three years in the 1980s and 1990s but there had not been any reported in the seven years before the 2014 event.

Mr Mackintosh said that the boreholes had been created to prove or disprove dissolution effects in support of planning applications.

However, his research suggested that these then triggered groundwater flows, creating new contamination pathways to cause gypsum dissolution and ground subsidence.

He said: "Not just invasive boreholes, but also quarrying activities routinely precipitate disturbance to groundwater flows, often related to pumping-out for de-watering purposes.

"Today, just south of Ripon, quarrying at Ripon City Quarry may be expected to cause gypsum dissolution and ground de-stabilization over a wide area."

New quarrying, soon to begin after being approved by North Yorkshire County Council, may create new problems for Ripon, according to Mr Mackintosh.

Ripon residents have called on Harrogate Borough Council to employ gypsum experts to minimise the risks of further sink holes appearing in the city.

However, Gaynor Allen of The Crescent, said she does not believe this latest incident or 'gypsum hysteria' will stop people from buying houses and moving to Ripon.

She said: "It shouldn't put buyers off as most of Ripon is totally sound; it is only a small area where the pockets of gypsum are troublesome.

"After all, the cathedral has stood for hundreds of years. Ripon has two ofsted outstanding schools, a very low crime rate, easy access to major road networks, and major companies are looking to invest in the city such as M&S.

"Ripon is getting better. It would be terrible if 'gypsum hysteria' took hold and turned home buyers away."